Homozygous in white patterns?

The theory on homozygous splash is that those are the ones with a higher expression of white and frequently blue eyes. They are not always deaf -- the deafness appears to run in certain families though. So a heterozygous splash (says the theory) will have "normal" white markings along the lines of socks, a snip or a blaze, and homozygous splashes will have white that pushes up onto the body and more white on the head, sometimes surrounding the eyes.

When I got Cory I posted him here to ask whether people think he is homozygous or heterozygous and the consensus here was that he is kind of in between. I see signs of splash in all three of his foals so far, but continued breeding records will show more definitely whether he is homozygous or heterozygous.

I'm in a rush so I'll let someone else answer about the other patterns. :)

[quote]HMZ tobiano exists.[/quote] Yep
[quote]HMZ frame = lethal white and won't live to reproduce.[/quote]Yep
[quote]HMZ sabino. Is it always all white? I am assuming not, since there are so many suspected expressions of sabino?[/quote] It is believed to be. The only sabino they have a test for now (Sabino 1) is heterozygous minimal markings, and homozygous at least 95% white.
[quote]HMZ splash? does that exist? If yes, is that the deaf form? :?[/quote] As Sara said it is theorized to exist yes. It is thought to be an incomplete dominant so heterozygous gives you minimal expression and homozygous expression gives you max expression. The cause of deafness is believed to be pigmentation cells not getting to the inner ear, and the part that allows them to hear, and that causes the deafness. This theoretically could happen in heterozygous, or homozygous form, but being that homozygous form is louder its more likely to happen on a homozygous horse.

[quote]
Fewspot and snowcap are their homozygous forms?[/quote] I believe so yes. [quote]Why different patterns?[/quote] I believe it is thought that there are two different genes that regulate which pattern a horse gets. One gives you leopards and few spots PATN1 and the other gives you you Blankets and Snowcaps PATN2.

LPlp PATN1 gives you leopard. LPLP PATN1 gives you few spot. So LPlp PATN2 gives you a blanket. LPLP PATN2 gives you snowcap.

That is at least how I understood it the last time it was presented to me. If that has changed I would absolutely LOVE LOVE LOVE to hear the new theory.

ETA:Fixed PATN1/2

Agreed with all the above... with one minor technicality. Leopard and fewspot are considered PATN1 instead of 2.

[quote="Sara"]The theory on homozygous splash is that those are the ones with a higher expression of white and frequently blue eyes. They are not always deaf -- the deafness appears to run in certain families though. [/quote]

But the higher white expressions (the white face/ear that leads to the inner ear problem) 'may' be hmz? :?
Related thought: is Gunner hmz? (he should have enough foals on the ground to tell?) Was Gambling man deaf? Are those two related?

[quote="Sara"]So a heterozygous splash (says the theory) will have "normal" white markings along the lines of socks, a snip or a blaze, and homozygous splashes will have white that pushes up onto the body and more white on the head, sometimes surrounding the eyes.[/quote]

But if splash equals the normal white markings, (socks and blazes, etc) then why don't hmz splashes happen all the time and in all breeds? :o Or do they? And if so, then what is the other cause for the splash that above mentioned studs display, since the 'wild' splash patterns are not as common as the normal white markings?

[quote="RiddleMeThis"] (hmz sabino all white?) It is believed to be. The only sabino they have a test for now (Sabino 1) is heterozygous minimal markings, and homozygous at least 95% white.[/quote]

But Clydesdales? Sabino is a breed trait. How do you not get hmz foals if you keep crossing parents that carry sabino? And as far as I know, there are no all white clydes?
(There was a European Clyde breeder a-board the last time. Is she still around?)

[quote="vneerland"]But the higher white expressions (the white face/ear that leads to the inner ear problem) 'may' be hmz? :? [/quote] Yes those markings MAY be on a horse that is homozygous. There is no test so we are all unsure of where the line between HZ and hz truly falls.
[quote]
Related thought: is Gunner hmz? (he should have enough foals on the ground to tell?) Was Gambling man deaf? Are those two related? [/quote] I personally believe gunner is homozygous. I do not think Gamblin Man was deaf, though I do not know for sure. I am also not sure if they are related, though they probably are at least distantly.

[quote]
But if splash equals the normal white markings, (socks and blazes, etc) then why don't hmz splashes happen all the time and in all breeds?[/qu :o Or do they?[/quote] Depends on your definition of "all the time." Its alos a matter of what is truly the minimal expression of a homozygous horse, and whats the maximal expression of a heterozygous horse? We could be seeing any amount of horses that have four high white legs and blaze and thinking hmm thats probably heterozygous when in actuality it may be homozygous instead. [quote]And if so, then what is the other cause for the splash that above mentioned studs display, since the 'wild' splash patterns are not as common as the normal white markings?[/quote]Are you talking about Gamblin Man and Gunner? If you are Im not really sure what your asking? Just because its not common doesn't meant thats not whats causing them to look like that.

[quote="RiddleMeThis"] Depends on your definition of "all the time." Its alos a matter of what is truly the minimal expression of a homozygous horse, and whats the maximal expression of a heterozygous horse? We could be seeing any amount of horses that have four high white legs and blaze and thinking hmm thats probably heterozygous when in actuality it may be homozygous instead. [/quote]

Yes, so there has to be something else at play inside the expressions of Splash.
I think wel can all agree that 'chrome' on a horse is not unusual, and happens in most breeds. But the loud expressions (example: gambling man) are much rarer. Between 2 hetrozygous splash horses, you'd at least expect 25% Hmz per breeding. So if the (very) loud expressions don't happen a lot in most breeds, that should lead to the conclusion that our theory is flawed or that we are missing pieces of the puzzle?

[quote]Are you talking about Gamblin Man and Gunner? If you are Im not really sure what your asking? Just because its not common doesn't meant thats not whats causing them to look like that.[/quote]

:D Not arguing that. They could well be. (Hmz) but if they are a possible Hmz expression why are horses that look like them not all over the place and common in most breeds? Unless. (see paragraph above)

Because maybe homozygotes don't have to be that loud. Maybe some white suppression genes hold others back. Maybe they had a boosting gene (both are/were LWO negative but have sabino).

We do see other examples like them. They're really not that rare. Just not as common as some other pattern expressions.

I would not be in the least bit surprised to find that suppressors are very wide spread since white markers were looked down on for so many years.

I'm personally not sure about the homozygous splash thoughts. I see a lot of Gypsy cobs and I believe that almost all would be homozygous splash. I believe that those chin spots, called sabino, is probably even splash. Thus splash can really be quite common. But just that it usually is never very loudly expressed due to so many years of selecting away from loud markings. Splash will be a hard one to really define I think as it's so often boosted by other patterns.
Cheers

Danni

I think the sabino "family" of low level markings is far more common than is minimal splash. I've been looking at parents of "cropout" splashes and progeny of loud ones for a while and I've got a pretty good feel for what minimal looks like. It's out there but it's not like [i]everywhere[/i].
Like with the arabians, splash is very rare there, I remember 5-6 years ago when it was thought to be nonexistent. It's very common in the painted breeds cause that's where many of the cropouts ended up, just not identified as common because the horse often has one or more other patterns that people define them by instead. (give someone a frame overo/splashed white and ask them what it is....overo :lol: the only one's normal people really take note of are the full blown splashes with no other patterns like gambling man and gunner, or at the most a tobiano splash like the gypsies or my mare.)
I belive my broodmare to be homozyygous and I bred her to what I see as a definite minimal (based on the face marking and progeny) and got myself a quite loud baby.(depending on definition of loud :laugh1 She's tobiano and splash and between the two of them most all the color got ate up) The same mare had been bred to a solid before that and gave me a minimal (with quite a classic minimal splash blaze).
Things do get a little muddly when the sabino patterns are also present. Like with Chase my deaf black splash/sabino. His pattern has very distinct characteristics of both and I dont know for the life of me if he's homozygous or hetero. Sabino seems to boost it up beyond what it would do on it's own.

As far as the chin white, thats been somewhat firmly linked as a sabino trait, ime minimal splashes are far more likely to have a blaze that stops at the upper lip or nose, the ones with the chin spot have other traits of sabino as well.

I'm wishy washy on the chin spot. I feel if it's a disconnected chin spot it is probably sabino. If the blaze curves all the way under to the chin (especially if it widens around the nostrils at all) it's probably splash. I think splash is very funny in the muzzle area. It like to cover the muzzle in white, but it also adds dark spots back into the nostrils and sometimes frontal moustaches almost like it's trying to break the white at the lip line. It's very weird.

I'd like to make a motion to assemble many (more) examples of splash (and sabino) expressions in this forums albums. 8-) Since we're still speculating about those.
Lacy isn't in there yet, is she, ACC?

Nope. Think she should be considering we know she's frame?

[quote="Morgan"]I've been looking at parents of "cropout" splashes and progeny of loud ones for a while and I've got a pretty good feel for what minimal looks like. It's out there but it's not like [i]everywhere[/i].
Like with the arabians, splash is very rare there, I remember 5-6 years ago when it was thought to be nonexistent.[/quote]

I know Khartoon Khlassic is called sabino. But in the definition here, wouldn't he be sabino and splash?

[quote]Things do get a little muddly when the sabino patterns are also present. Like with Chase my deaf black splash/sabino. His pattern has very distinct characteristics of both and I dont know for the life of me if he's homozygous or hetero. Sabino seems to boost it up beyond what it would do on it's own.[/quote]

For some reason, I was picturing the face white on deaf spashes to be higher up around the ears :o I am sure that is related to my background in dogs (deaf dalmatians,for example) But yes, Chase to me is very much splash first, sabino second. Is there any reason to assume that sabino is needed to 'get' the deafness?

[img]http://www.equine-color.info/gallery2/m…]

[quote]As far as the chin white, thats been somewhat firmly linked as a sabino trait, ime minimal splashes are far more likely to have a blaze that stops at the upper lip or nose, the ones with the chin spot have other traits of sabino as well[/quote]
Yes, but not all sabino's have chin white, right? So it could be found in both sabino and splash? Or maybe yet another result of the patterns boosting each other?

Maybe this was already addressed and I skimmed over it, but remember that socks and blazes (normal chrome) can be caused by sabino as well as splash so you wouldn't expect to see loud, homozygous splashes in every breed that has individuals with chrome.

also, I think we don't see more loud homozygous individuals in breeds like Welshes (where splash is very common) because breeders have learned not to breed two splashed white ponies. They know that risks a broken colored foal which until very recently would not be given papers.

[quote]I know Khartoon Khlassic is called sabino. But in the definition here, wouldn't he be sabino and splash? [/quote]
yes, he's one of the known splashes :)
[quote]For some reason, I was picturing the face white on deaf spashes to be higher up around the ears :o I am sure that is related to my background in dogs (deaf dalmatians,for example) But yes, Chase to me is very much splash first, sabino second. Is there any reason to assume that sabino is needed to 'get' the deafness?

[img]http://www.equine-color.info/gallery2/m…]
Ive seen a deaf one with even less white, :shock: wish I still had the picture...
the deafness is just caused by what goes on in the inner ear, which you cant really tell by looking at the skin except that the white is "close". Horse is 3 dimentional :) Just as the eyes can be blue far from the blaze the ear can also be affected, and vice versa, a horse with a great big white face doesnt have to be deaf. Actually though I wonder how common unilateral deafness is since one of the traits of the Splash pattern is to be lopsided. That is imo extremely dificult to diagnose on your own.
It's quite possible that Chase is a homozygous, I just dont know. His sire was marked just like my broodmare and had a habit of throwing bald faces with certain mares btu I dont really remember what his dam was like except the distinct impresion of Frame Overo, this was before I even knew what Splash was so I wasnt at all looking for the minimal form.

somewhat random but: http://www.sabinohorseregistry.com/" onclick="window.open(this.href);return false;
wth???? :laugh1 :BH :hammer I about choked on my tea :laugh1 :laugh1 :laugh1 :laugh1

Ah yes the 'pretty patterned horse' registry.......

Yeah I find that site hilarious myself. Delusional Arab breeders (some of them anyway).

[quote="accphotography"]Yeah I find that site hilarious myself. Delusional Arab breeders (some of them anyway).[/quote]

White in arabs is SO discouraged that I find it a step forward.... WA Outrageous was actually asked to leave the ring once....Another point is that it is a place where a horse who might not otherwise be registered. At least there is some record and place for them.

Did they think she was not purebred?